Means for making dentures



A. H. CHENOWETH MEANS FOR MAKING DENTURES 2 Sheets-Sheet 1 Filed June21, 1937 HIS ATTORNEYS Dec. 24, 1940.

Dec. 24, 1940. A. H. CHENOWETH MEANS FOR MAKING DENTURES Filed June 21,1937 2 Sheets-Sheet 2 g mvzmo? H1: ATTORNEYS Patented Dec. 24, 1940UNITED STATE-s PATENT OFFICE MEANS FQR MAKING DENTURES Avery HobartChenoweth, Mason City, Application June 21, 1937, Serial No. 149,527

2 Claims, (Cl. 1833) My invention relates to dentures, and includesamong its objects and advantages the provision of an improved drytechnique of and means for making dentures.

In the accompanying drawings:

Fig. 1 is a perspective view of my novel press and oven;

Fig. 2 is a front view with the door removed and certain parts brokenaway for the sake of 1 clearness; I

Fig. 3 is a sectional view along the line 3-3 of Fig. 2; i

Fig. 4 is a sectional view along the line 4-4 of Fig. 2;

Fig. 5 is a sectional view along the line 5-5 of Fig. 4; I

Fig. 6 is a sectional view along the line 6-8 of Fig. 2;

Fig. 7 is a top plan view of my dental flask;

Fig. 8 is a sectional view along the line 8-8 of Fig. 7; r

Fig. 9 is a sectional view along the-line 9--9 of Fig. 7; and

Fig. 10 is a diagrammatic view of theelectric circuit.

In the embodiment selected to illustrate my invention, I make use of anoven I8 comprising side walls I2 and I4, a back wall I6, a bottom I8,and a top 28. A door 22 is hingedly connected at 24 with the frontvertical edge of the wall I4.

Walls I2, I4 and I6 comprise two spaced metallic plates 26 and 28between which insulating material 38 is provided. Plate 26 is providedwith flanges 32 arranged in overlapping relation 5 with flanges 34 ofthe plate 28 and connected into a unitary structure by welding. The door22 comprises spaced metallic plates 36 and 38 between which insulatingmaterial. 40 -is positioned. Plate 38 is shaped to provide ledges 42 4along its four edges, which ledges overlap the forwardedges of the wallsI2 and. I4, the bottom I8 and the top 28. Plates 36 and 4Ilmay be provided with overlapping flanges. 44secured into a unitary structure bywelding.

5 Bottom-I8 comprises spaced metallicplates 46 and between whichinsulation 56. is provided. Plate 46 is bent to provide an L-shapedflange 52 withinwhich the lower edge of the side walls I2 and I4 and theback wall I6 rest. Plate, 48 may 50 be welded to the flange 52 and theplate is provided with ajflange 54 which may be welded at 56 to theplate 28Iwhich defines the outer faces of the side walls I2 and I4 andthe back I6. Plate 28 is shaped to provide legs.58 atits lower Top 28comprises two spaced plates 68 and 62 arranged to support insulation 64.Plate 68 includes an L-shaped flange 66, while the plate 62 is providedwith a flange 68 co-operating with the flange 66 for housing the upperedges of the 5 side walls I2 and. I4 and the back wall I6. Flange 68 maybe welded to the plate28, while the flange 66 may be welded to the plate62. The ledge 42 along the upper edge of the door 22 presses against theflange 68 of the plate 62 along the 10 forward edge of the top 28. InFig. 2, I illustrate the bottom I8 as being provided with a flange 18comprising an extension of the plate 46 against which the lower ledge 42of the door 22 rests. 15

Within the oven I8 I mount a press I2. The press comprises a base plateI4 welded at 16 to the side walls I2 and I4. Uponthebase plate 14 Imount a plate I8 which is secured in position by bolts 88 passingthrough the base plate 30 I4 and having threaded relation with the"plate I8. Four vertical bars 82 have threaded connection with the plate"as indicatd at 84. I The upper ends of the bars 82 terminate in reducedshanks 86 passing through openingsin the flange 25 88 of a head 98. Nuts92 have threaded relation with the shanks 86 for securely fastening theflange 88in position and for supporting the head 98 in fixed relationwith respect to the plate I8. I v I I g 30 A pressure plate 94 is boredto loosely receive the bars 82.- Pressure plate 94 may be raised andlowered. on the bars 82 which guide the pressure plate. In Fig. 1, Iillustrate a screw 96 as having threaded relation with the threaded 35bore 98 in the head 98. -At the lower end of the screw 96, Iprovide acircular flange I86 of larger diameter than the screw 96. Pressure plate94 is recessed at I82 sufficiently far to bring the upper ace of theflange I 88 flush with the top face of 4 the plate. A retaining washerI84 is attached to the pressure plate 94 by bolts I86 for. rotatablyconnecting the flange I88 with the pressure plate.

It will thus'be seen that the flange I88 is rotatably related -to thepressure plate 94 but any 5 Vertical movement of the screw 96 as it isro- .tated imparts vertical movement to the pressure plate 94. Thisplate is maintained in parallel relation with the plate 18 in allpositions of adjustment. I p

Screw 96. terminatesin a shaft I68 which is rotatably supported within asleeve II8 connected with the top 28. The outer end of the shaft I88 maybe provided with a handle II2 to facilitate turning. Nuts 92 hold theflange 88 in fixed relation with the guide rods 82 so that rotarymovement of the screw 86 is translated into vertical movement of thepressure plate 94.

rality of depending eyes I20 provided with in-..

sulating liners I22 through which the heating element I24 is threaded.Fig. 4 illustrates the staggered arrangement of the eyes' I20 so as todistribute the heating element-substantially over the entire area of theplate.

The top 20 is provided with eyes I26 of the same construction as theeyes I20 through which a heating element {28 is threaded. The ends ofthe element I28 are electricallyconnected with terminals" I30 carried bya socket I32 anchored to the rear wall I6 by bolts I34. The ends of theheating element I24 are electrically connected with prongs I36 arrangedto have electrical connection with the socket I32. Prongs I36 areanchored on a lip I30 formed from the plate H6.

Plate I I 6 is removably retained within theoven I0. Because of theprongs I36, the plate may be removed as a unit with the heating elementI24. Electrical connection is established between the heating elementI24 and the socket I28 by merely pushing the plate II 6 home. Within theoven I0, I mount a conventional thermostat I40. I provide the rear wallI6 with an Opening I42 for accommodating the electric cord I44 providedwith the usual plug I46 for electrical connection with a wall outlet.Cord I44 hasits wire I48 electrically connected with one of theterminals I30, while the other wire I 50 is electrically connected withthe thermostat I bya wire I52. The thermostat may be regulated as totemperature response through the medium of a knob I54 located exteriorlyof the side I2. This knob may be provided with a needle I56 arranged inreading relation with'gradu'ations I58 in terms of temperature.Thermostats are well known in the art and need not be described infurther detail. In Fig. 10, I illustrate the electric circuit. 'In thiscircuit I have included a clock I60 for controlling the conventionalswitch I62 so that the current may be shut off automatically after apredetermined time. The clock may be exterior of the oven I0 at anydesirable place.

Figs. 7, 8 and 9 illustrate the dental flask. The flask comprises abottom section I64, a top section I66 and a cover I 68. The cover I 68is provided with two fixed guide pins I'I0 arranged to be inserted inbores I12 and H4 in the sections I64 and I66, respectively. The boresI12 and H4 lie within ribs I16 projecting laterallyof the flask and theribs and pins I10 are provided with aligned openings II8 for thereception of the reaches I of a U-shaped lock wire I82. Two wires areassociated with the flask; Section I 64 may be provided with recesses I8for the reception of lugs I86 carried by the section I66 forregistration purposes. In Fig. 2, I illustrate the plate I8 as beingprovided with. a slight projection I88 arranged to lie within thedepression I90. in the bottom of the section I64. Pressure plate 94 isalso provided with a projection I92 which lies within a depression I94in the cover I68. Thus, the flask may be accurately oentered withrespect to the axis of the screw 96. This screw is of relatively largediameter, which is also true of the flange I00 so that pressure forceswill be distributed substantially over the entire area of the pressureplate 94. The large diameter screw distributes pressure forces uniformlythroughout the plate 94, which aids in maintaining the pressure plate inparallel relation with the plate'Ifl. The large diameter screw incombinationwith the guide rods 82 operate to maintain uniform pressurethroughout the entire top and bottom of the flask positioned between thetwo plates.

, In connection with the structure so far described, make use of a dryheat method of vulcanization in connection with such materials asrubber, synthetic rosin such as cellulose, luxene,

etc. The denture cast or mold is positioned in the bottom section I64previously provided with the proper amount of plaster of Paris or stonecommon to the art. After the plaster has set it is treated with aseparating fluid in the'usual manner. The upper section I66 is thenplaced in position on the section I64. A creamy mix of plaster of Parisis poured into the flask up to its .top. The cover I68 is then placed inposition with the pins II0 located within the bores I12 and I14, afterwhich the spring lock wires I82 are placed in position as illustrated inFig. 9. 'At this time the flask is set aside for at least an half houruntil the plaster is hard.

After the plaster has set, the flask is placed in the oven I0 and thethermostat is adjusted for a heat of about 200 F. I The flask ismaintained under this temperature for about ten to fifteen minutes.After heating, the flask is a removed from the oven and the spring lockvwires I82 removed. The sections of the flask may now be separated. Thewax in which the teeth have been set is soft but not in a liquid stateand can be lifted from the plaster mold. At this time all the teethshould be taken from the mold and kept in proper relationship. If somewax remains on the cast or mold it should be removed with a sharpinstrument or wiped clean with chloroform.

After separationof the flask, and the removal of the wax remains fromthe cast or mold, the two sections of the flask are kept apart andplaced in the oven to remove moisture. The thermostat is set to maintaina temperature of 300 F., and the time required to remove the moisture isapproximately two hours. Higher temperatures may be employed, but I havefound that it is not advisable to employ a temperature in excess of 350F. A temperature of 225 F. maybe employed for an all night drying job.In providing the oven with the time clock I60 and the thermostat I40,temperature and time are controlled automatically without the attentionof the operator. After the moisture has been entirely evaporated, theflask is taken from the oven and placed on the laboratory bench to coolfor a few minutes. A liquid comprising Celluloid dissolved in acetone ispainted overthe entire cast or mold with the exception of the areaoccupied by the teeth. The teeth should be cleaned of. all wax andplaced in the mold in their proper places.

With the flask still separated it is again placed in the oven at atemperature. of about 215 F. for ten minutes; The section of the flaskcontaining the teeth is removed and ground Luxene is placed around theteeth and the mold completely filled. When the Luxene becomes semiliquidthe other section of the flask is taken from the oven and placed inposition on its companion part. The assembled flask is then placed inthe press and the screw 96 turned slowly until the flask is correctlyclosed.

The spring lock wires I82 are then slipped into place the flask removedfrom the press and placed on one of the shelves I96 for the curingprocess. A temperature of 250 F. is maintained in the oven for about twohours and thirty minutes, but the temperature should not be raised tothis degree within less than twenty minutes. After the curing process,the flask is permitted to cool and is then removed and placed in water.The trimming, filing and polishing are done in the customary manner. I

In connection with Celluloid materials, such as are known in the tradeas Hecolite, Parfait, Fiberloid, Alcolite, etc., no drying out isnecessary. In connection with these materials, after the wax has beenremoved from the cast or mold the dental material is placed between thetwo halves of the flask and the flask placed in the press. Thethermostat is set at the desiredtemperature advisable for the specificmaterial employed. The temperature is so constant that the pressingprocess is exceedingly simple and easy. After the flask has been in thepress for thirty minutes at the desired temperature, the screw 96 isturned down slowly. Ten to fifteen minutes time should be consumed inclosing the flask. After the flask is closed, the spring lock wires I82are placed in position and the flask may be removed from the oven andpermitted to cool slowly. In connection with rubber, the technique isidentical as in connection with Luxene except for the curing time. Thevulcanizing of rubber should be done in the manner advised by themanufacturer.

The rear wall It is provided with a vent opening I98 for the escape ofvapors in the event that the denture material should catch on fire. Thevent opening prevents the occurrence of explosions. In connection withthe dry heat method of vulcanization, I eliminate the necessity for hotwater or steam. The flasks when removed from the oven after curing areclean and dry, which is a desired advantage over the steam vulcanizingsystems. The oven II] is well insulated and the'radiation of heat hasbeen reduced to a minimum. The thermostat I40 maintains the heat at thedesired temperature so as to insure proper heating but with no waste.The oven is easily operated. Because of the clock 160 the system islargely automatic. I

eliminate the necessity for nut and bolt fastenings and the oven may beopened through the medium of the door 22. Because of the door, thecuring process may be watched in addition to permitting access to theinside of the oven. According to my method, the plaster molds remainhard and dry and the finished dentures fit accurately. They are harder,tougher and more dense than dentures made according to conventionalsteam pressure methods.

In Figs. 1 and 4, I have illustrated the door 22 as being provided witha handle 20!] rotatably mounted and including a lug 202 arranged to liebehind a lug 204 on the wall l2 for latching the door in its closedposition.

Without further elaboration, the foregoing will so fully explain myinvention that others may, by applying current knowledge, readily adaptthe same for use under various conditions of service.

I claim:

1. In a device of the type described, a supporting floor for a dentalflask, a head having a threaded bore, means for securing the head infixed relation with the supporting floor, a flask pressure plateslidably guided by said means and paralleling said supporting floor, ascrew having an annular flange at one end located on the pressure plate,the'flange being of larger diameter than the screw and the latter havinga crosssectional area substantially equal to the area of theflaskengaged by the pressure plate, means fastened to the pressure plate andextending over said flange for rotatably connecting that end of thescrew with the pressure plate, and means for turning the screw.

2. In a device of the type described, a supporting floor for a dentalflask, a head having a threaded bore, means for securing the head infixed relation with the supporting floor, a flask pressure plateslidably guided by said means and paralleling said supporting floor, ascrew having an annular flange at one end located on the pressure plate,the flange being of larger diameter than the screw and the latter havinga crosssectional area substantially equal to the area of the flaskengaged by the pressure plate, said pressure plate having an annularledge against which the peripheral margin of the flange contacts, andmeans fastened to the pressure plate and extending over the annularflange for rotatably connecting that end of the screw with the pressureplate.

AVERY HOBART CHENOWETH.

